Implantation of biliary stent structures provides treatment for various conditions, such as obstructive jaundice. Biliary stenting treatment approaches can be used to provide short-term treatment of conditions such as biliary fistulae or giant common duct stones. Biliary stents may be implanted to treat chronic conditions such as postoperative biliary stricture, primary sclerosing cholangitis and chronic pancreatitis.
Although adequate, a biliary stent can become occluded once implanted within a bile duct, as an encrustation of amorphous biological material and bacteria (“sludge”) accumulates on the surface of the stent, gradually obstructing the lumen of the stent. Biliary sludge is an amorphous substance often containing crystals of calcium bilirubinate and calcium palimitate, along with significant quantities of various proteins and bacteria. Sludge can deposit rapidly upon implantation in the presence of bacteria. For example, bacteria can adhere to plastic stent surfaces through pili or through production of a mucopolysaccharide coating. Bacterial adhesion to the surface of a stent lumen surface can lead to occlusion of the stent lumen as the bacteria multiply within a glycocalyx matrix of the sludge to form a biofilm over the sludge within the lumen of an implanted drainage stent. The biofilm can provide a physical barrier protecting encased bacteria from antibiotics. With time, an implanted biliary stent lumen can become blocked, thereby undesirably restricting or blocking bile flow through the biliary stent.
Once implanted, a biliary stent may also allow reflux of duodenal fluid in the common biliary duct. Such reflux may cause irritation leading to stricture of the common bile duct. Such obstruction is undesirable.
There exists a need in the art for an implantable medical device that prevents or reduces the biofilm and sludge deposition process on implantable drainage stents, such as biliary stents; and prevents or reduces reflux of duodenal fluids in the common bile duct.